Quick Answer
The answer is configuring file-level permissions, as this is the most cost-effective control for preventing unauthorized access to customer data on a local file server. File-level permissions, such as NTFS permissions on Windows or POSIX ACLs on Linux, provide granular access control by directly restricting which users or groups can read, write, or modify specific files and folders, all without requiring additional hardware or complex management overhead. On the CISA exam, this question tests your understanding of cost-effective access control mechanisms within a small business context, where budget constraints make simple, built-in operating system controls preferable over expensive solutions like full-disk encryption or dedicated access management appliances. A common trap is choosing a more complex or costly option, such as implementing a full identity management suite, when the scenario explicitly asks for the most cost-effective approach. Remember the memory tip: for small budgets, think “files first” — file-level permissions are the cheapest and most direct lock on the data itself.
This CISA practice question tests your understanding of protection of information assets. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A small business wants to protect customer data stored on a local file server. Which of the following is the MOST cost-effective control to prevent unauthorized access?
Enable detailed audit logs
Why wrong: Audit logs are detective, not preventive.
Configure file-level permissions
File permissions are a direct and low-cost way to control access.
Implement full-disk encryption
Why wrong: Full-disk encryption protects against physical theft but is more costly and not the most targeted control.
Deploy biometric authentication
Why wrong: Biometrics are typically more expensive for a small business.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Configure file-level permissions
Configuring file-level permissions (e.g., NTFS permissions on Windows or POSIX ACLs on Linux) is the most cost-effective control because it directly restricts which users or groups can read, write, or modify specific files and folders on the server. This granular access control prevents unauthorized access without requiring additional hardware or complex management, making it ideal for a small business with limited budget.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Enable detailed audit logs
Why it's wrong here
Audit logs are detective, not preventive.
Configure file-level permissions
Why this is correct
File permissions are a direct and low-cost way to control access.
Related concept
Read the scenario before looking for a memorised answer.
Implement full-disk encryption
Why it's wrong here
Full-disk encryption protects against physical theft but is more costly and not the most targeted control.
Deploy biometric authentication
Why it's wrong here
Biometrics are typically more expensive for a small business.
Common exam traps
The trap here is that candidates often confuse detective controls (audit logs) or encryption (which protects data at rest) with preventive access controls, leading them to choose a more expensive or less effective option instead of the simple, direct file permission configuration.
Detailed technical explanation
File-level permissions rely on access control lists (ACLs) that associate security identifiers (SIDs) with specific rights such as Read, Write, Execute, or Full Control. In Windows, these are enforced by the NTFS file system driver during every file operation, checking the user's token against the ACL's ACEs. A common subtlety is that effective permissions are the result of combining share permissions and NTFS permissions, with the most restrictive rule applying when both are used.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
What to study next
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FAQ
Protection of Information Assets — This question tests Protection of Information Assets — Read the scenario before looking for a memorised answer..
The correct answer is: Configure file-level permissions — Configuring file-level permissions (e.g., NTFS permissions on Windows or POSIX ACLs on Linux) is the most cost-effective control because it directly restricts which users or groups can read, write, or modify specific files and folders on the server. This granular access control prevents unauthorized access without requiring additional hardware or complex management, making it ideal for a small business with limited budget.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
This CISA practice question is part of Courseiva's free ISACA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CISA exam.
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